I think emoji are great at complimenting “traditional” written language. They’re really good at conveying emotion, which text isn’t great at.
I don’t think it’s destroying any language development, and if they were, then I find no reason to be mad at that fact.
Also: Apple just revamped all their emoji. http://www.apple.com/newsroom/2016/08/apple-adds-more-gender-diverse-emoji-in-ios-10.html